Identification of QTLs influencing wood property traits in loblolly pine ( Pinus taeda L.). II. Chemical wood properties.

Chemical wood property traits were analyzed for the presence of quantitative trait loci (QTLs) in a three-generation outbred pedigree of loblolly pine ( Pinus taeda L.). These traits were assayed using pyrolysis molecular beam mass spectrometry and include mass spectrum peak intensities associated with carbohydrates, alpha-cellulose and hemicellulose sugars, and lignin. Models for projection to latent structures (PLS) were used to also estimate the chemical composition of cell walls (i.e., alpha-cellulose, galactan and lignin) from mass spectrum data using multivariate regression. Both earlywood and latewood fractions from the fifth annual ring were analyzed for each trait. An interval mapping approach designed for an outbred pedigree was used to estimate the number of QTLs, the magnitude of QTL effects, and their genomic position. Eight unique QTLs influencing cell wall chemistry were detected from multiple peak intensities and/or PLS estimates using the one- and two-QTL models. Significant differences in chemical contents were observed among the populations from North Carolina vs Oklahoma, and results from QTLxenvironment analyses suggest that QTLs interact with environmental location. QTLs should be verified in larger experiments and in different genetic and environmental backgrounds. QTL mapping will help towards eventually identifying genes having a major effect on chemical wood properties.

Anchored reference loci in loblolly pine (Pinus taeda L.) for integrating pine genomics.

Anchored reference loci provide a framework for comparative mapping. They are landmarks to denote conserved chromosomal segments, allowing the synthesis of genetic maps from multiple sources. We evaluated 90 expressed sequence tag polymorphisms (ESTPs) from loblolly pine (Pinus taeda L.) for this function. Primer sets were assayed for amplification and polymorphism in six pedigrees, representing two subgenera of Pinus and a distant member of the Pinaceae, Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). On average, 89% of primer sets amplified in four species of subgenus Pinus, 49% in one species of subgenus Strobus, and 22% in Douglas-fir. Polymorphisms were detected for 37-61% of the ESTPs within each pedigree. Comparative mapping in loblolly and slash pine (P. elliottii Englm.) revealed that ESTPs mapped to the same location. Disrupted synteny or significant disruptions in colinearity were not detected. Thirty-five ESTPs met criteria established for anchor loci. The majority of those that did not meet these criteria were excluded when map location was known in only a single species. Anchor loci provide a unifying tool for the community, facilitating the creation of a "generic" pine map and serving as a foundation for studies on genome organization and evolution.

The intensity and duration of primary Heligmosomoides polygyrusinfection in TO mice modify acquired immunity to secondary challenge.

The effect of dose and duration of immunizing infections of Heligmosomoides polygyrus on protection against homologous challenge was studied in female TO mice. Primary infections were terminated at various levels with pyrantel embonate (adult infections) or ivermectin (larval infections) and mice were then challenged with 500 infective larvae (L3). The level of protection to secondary challenge positively correlated with the intensity of the primary immunizing infection but truncation of larval infection produced significantly better protection than termination of the adult nematode infection. The duration of the primary larval infection (1-6 days) positively correlated with the level of protection to secondary challenge, antibody responses and the proportion of circulating eosinophils. Histological changes in the gastrointestinal tract, peripheral leucocytic changes and antibody responses of the mice to H. polygyrus adult somatic antigens indicate both a cellular and humoral basis of host immunity to secondary challenge. Although the TO mice are slow responders in that they harbour chronic infections, immunization by intramucosal killing of the larval stage produced strong protection against secondary challenge infection. The presence of dead immunogenic larval stages within the intestinal wall may well be an important factor, since it exposes the host to stage specific antigens at an appropriate location. The implications of the findings for the control of gastrointestinal nematode infections are also discussed.

Heligmosomoides polygyrus and Trypanosoma congolense infections in mice: effect of immunisation by abbreviated larval infection.

Concurrent African trypanosome and gastrointestinal helminth infections are prevalent in sub-humid savannah where they are endemic. However, acquired resistance in animals varies with their responder status and exposure. As a guide to study in the definitive hosts, the effects of Trypanosoma congolense infection on the development and maintenance of homologous Heligmosomoides polygyrus resistance were investigated in outbred TO mice. These mice were immunised by abbreviation of larval infection. Immune or naive mice were either infected with 500 infective larvae (L3) of H. polygyrus and/or 10(4) bloodstream forms of T. congolense or were not infected. The outcome of infection was monitored by routine parasitological and immunological techniques for 30 days after the day of the T. congolense infection. Significantly more immune mice concurrently infected with both parasites survived than did immune mice in which H. polygyrus was superimposed on a 10-day-old T. congolense infection. Although all the mice in this latter group died before the end of the experiment, larval immunisation prolonged their survival, relative to similarly treated naive mice. The antibody titres to H. polygyrus in the sera of immune mice challenged with H. polygyrus alone were significantly higher than those of immune mice concurrently infected with both parasites but the levels of protection obtained were comparable. It is concluded that T. congolense may not completely block the strong acquired resistance induced by abbreviated H. polygyrus larval infection in TO mice but is capable of interfering with protective responses, especially if the trypanosome infection occurs prior to H. polygyrus challenge infection.

A consensus map for loblolly pine (Pinus taeda L.). I. Construction and integration of individual linkage maps from two outbred three-generation pedigrees.

A consensus map for loblolly pine (Pinus taeda L.) was constructed from the integration of linkage data from two unrelated three-generation outbred pedigrees. The progeny segregation data from restriction fragment length polymorphism, random amplified polymorphic DNA, and isozyme genetic markers from each pedigree were recoded to reflect the two independent populations of parental meioses, and genetic maps were constructed to represent each parent. The rate of meiotic recombination was significantly greater for males than females, as was the average estimate of genome length for males (1983.7 cM [Kosambi mapping function (K)]) and females [1339.5 cM(K)]. The integration of individual maps allows for the synthesis of genetic information from independent sources onto a single consensus map and facilitates the consolidation of linkage groups to represent the chromosomes n = 12 of loblolly pine. The resulting consensus map consists of 357 unique molecular markers and covers approximately 1300 cM(K).

Comparative mapping in loblolly and radiata pine using RFLP and microsatellite markers.

Genetic linkage maps were constructed for loblolly pine (Pinus taeda L.) and radiata pine (P. radiata D. Don) using a common set of RFLP and microsatellite markers. The map for loblolly pine combined data from two full-sib families and consisted of 20 linkage groups covering 1281 cM. The map for radiata pine had 14 linkage groups and covered 1223 cM. All of the RFLP probes readily hybridise between loblolly and radiata pine often producing similar hybridisation patterns. There were in total 60 homologous RFLP loci mapped in both species which could be used for comparative purposes. A set of 20 microsatellite markers derived from radiata pine were also assayed; however, only 9 amplified and revealed polymorphic loci in both species. Single-locus RFLP and microsatellite markers were used to match up linkage groups and compare order between species. Twelve syntenic groups were obtained each consisting of from 3 to 9 homologous loci. The order of homologous loci was colinear in most cases, suggesting no major chromosomal rearrangements in the evolution of these species. Comparative mapping between loblolly and radiata pine should facilitate genetic research in both species and provide a framework for mapping in other pine species.

Expression of acquired immunity to Heligmosomoides polygyrus in mice concurrently infected with Trypanosoma congolense.

The effects of concurrent Heligmosomoides polygyrus and Trypanosoma congolense infection on the expression of acquired resistance to homologous nematode challenge were studied in female outbred TO mice. Mice were infected with 500 infective larvae (L3) of H. polygyrus and the infection was terminated by anthelminthic treatment on Day 12, when the worms were adults. Eight days later sub-groups of these pre-exposed mice, and of similar mice which had not experienced the previous infection with H. polygyrus, were either simultaneously infected with 500 L3 of H. polygyrus and 10(4) bloodstream forms of T. congolense, or with only one of these parasites, or were not infected. The experiment was monitored by routine parasitological and immunological techniques, including quantitative assessment of worm burden, trypanosome parasitaemia, growth of nematodes and measurement of the parameters reflecting pathological and antibody responses for 30 days after immunization. Concurrent H. polygyrus and T. congolense infection resulted in abrogation of the partial immunity against challenge infection with H. polygyrus in the pre-exposed mice, and in depressed humoral antibody responses following infection. Mortality was greatly reduced in pre-exposed mice infected with T. congolense alone compared to naive mice. The growth of male H. polygyrus worms was not affected by either the immune or infection status of their host. Although the increased size of the female worms from pre-exposed and then concurrently infected mice compared to similar mice infected only with H. polygyrus was significant, the egg production per worm was not affected.

Studies on helminthosis at the Centre for Tropical Veterinary Medicine (CTVM).

The research work relating to helminths, which has been conducted within the Helminthology Section of the CTVM, often in collaboration with colleagues from the tropics is reviewed and placed into a historical perspective. The research has, in the main, concentrated on the trematodes Fasciola hepatica and Fasciola gigantica and the cestodes Taenia saginata and Taenia solium, but work on other parasites including gastro-intestinal nematodes is also considered. All of these parasites are of obvious veterinary/economic importance particularly in the tropics and subtropics. While the zoonotic importance of T. saginata and T. solium has been recognised for many years, it is only more recently that the zoonotic impact of Fasciola spp. has been generally acknowledged.

Heligmosomoides polygyrus and Trypanosoma congolense infections in mice: a laboratory model for concurrent gastrointestinal nematode and trypanosome infections.

A murine model using Heligmosomoides polygyrus and Trypanosoma congolense has been developed for studying the effects of concurrent chronic gastrointestinal nematode and trypanosome infections. Female outbred mice were infected either with 500 infective larvae (L3) of H. polygyrus or with 10(4) bloodstream forms of T. congolense or both. In concurrent infections, animals were dosed with both parasites simultaneously or the trypanosomes were injected 5 or 10 days after the mice were infected with the nematode. The course of infection was monitored by routine parasitological and immunological techniques for 30 days after the H. polygyrus infection. Concurrently infected mice were severely compromised, except when T. congolense was superimposed on a 10-day-old (adult) H. polygyrus infection. In H. polygyrus-infected mice, simultaneous or subsequent infection with trypanosomes did not markedly influence worm establishment or fecundity, but the female worms were slightly stunted. Surviving mice displayed a markedly reduced antibody response to H. polygyrus antigens and a slightly reduced antibody response to T. congolense antigens.

Resistance to benzimidazole anthelmintics by trichostrongyles in sheep and goats in north-west Cameroon.

Following the routine use of tiabendazole at monthly intervals for several years, the trichostrongyle parasites of sheep and goats on a government research station in North-West Cameroon had become resistant to benzimidazole anthelmintics.

Protein antigens in the cyst fluid of Taenia saginata cysticerci.

Taenia saginata cyst fluid proteins from 4, 8, 12 and 16-week-old cysticerci were analysed by a combination of direct 125I radio-isotope labelling, immunoprecipitation using a panel of sera from infected cattle infected with T. saginata and SDS-PAGE. Protein antigens of 12, 14, 16, 20 and 26 kDa were identified in all of the cyst fluids examined. These were immunogenic and were precipitated by serum taken from cattle from 8 weeks after infection onwards and were therefore considered to be of diagnostic potential. A 185 kDa protein antigen found only in the cyst fluid of 4-week-old cysticerci and a 43 kDa protein antigen first detected in cyst fluid from 8-week-old cysticerci were also identified but were considered to be of more limited diagnostic potential due to their restricted presence. An apparently non-immunogenic 67 kDa protein, found in all the cyst fluids examined, may have been host serum albumin.

Developmental changes in proteins and glycoproteins revealed by direct radio-iodination of viable Taenia saginata larvae.

Direct surface 125I radio-isotope labelling techniques and SDS-PAGE analysis were used to compare the proteins and lentil-lectin adherent glycoproteins of the bovine stage of viable Taenia saginata larvae at three points in their development, the invasive oncospheres, immature (4-week-old) and mature (12 to 16-week-old) cysticerci. Some proteins and glycoproteins were present on all three of the ages of the parasite examined but there were also distinct age-specific proteins and glycoproteins detected on oncospheres and 4-week-old cysticerci and a marked difference between the protein/glycoprotein profiles of the parasite was apparent at these earlier stages of development and the mature cysticeri. The latter were characterized by the presence of high, 160-200 kDa molecular weight, lysine rich, glycoproteins, whereas small 16 and 18 kDa glycoproteins and a reduction-sensitive 23 kDa glycoprotein were first detected on 4-week-old immature cysticerci. Antigenic characterization of the isotope-labelled proteins and glycoproteins by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS-PAGE analysis indicated that relatively few proteins were precipitated by sera from T. saginata-infected cattle as compared to the glycoproteins. However, both protein and glycoprotein antigens of possible protective and/or diagnostic significance were identified from oncospheres and cysticerci. Of particular note were low molecular weight oncospheral proteins and low and high molecular weight cysticercal glycoproteins. The immunogenicity of these protein and glycoprotein antigens of T. saginata larvae and their age-related changes are of relevance to the design of diagnostic assays, vaccines and possibly to the survival of this parasite in its bovine host.

Disease and mortality in small ruminants in the North West Province of Cameroon.

Mortality rates and the prevalence of disease were assessed in 115 flocks of traditionally managed sheep and goats in two Divisions of the North West Province of Cameroon by means of a questionnaire to the owners. The mortality rate was significantly higher in sheep than in goats and also higher in young stock than in adults. Tethering the animals during the day resulted in significantly lower mortality in both adult and young sheep and also in kids. Disease problems of small ruminants, identified on the basis of signs reported by their owners, included intestinal parasitism, especially helminthiasis, tick infestation and associated diseases, pneumonia, goat plague (peste des petits ruminants) and Oestrus ovis infestation. Treatment of sick animals was only practised on a very small scale, often by possibly ineffective traditional methods. The owners identified tick infestation and diarrhoea as common causes of death. Recommendations are made on control measures suitable for application in this area.

Management and productivity of small ruminants in the north west province of Cameroon.

A survey showed that in the North West Province of Cameroon 92% of the farmers rear goats as against only 21% who rear sheep. The main constraint on sheep husbandry appeared to be a traditional belief that keeping sheep adversely affects a woman's fertility. Flock sizes are small (three to 48, median seven) but there was some tendency towards larger numbers in mixed flocks. There were considerably more females than males. Six systems for managing small ruminants were identified. The most widely practised was housing at night and tethering in daytime during the cropping season with either tethering or free-range grazing during the daytime in the non-cropping season. The most common housing system was an enclosed shed with walls of sticks, tree fern or bamboo. Floors of planks laid on the earth or slightly raised were used by about 48% of the farmers while 22% constructed raised slatted floors. Most farmers gave their animals salt on a more or less regular basis but otherwise intentional feed supplementation was rare. About 43% of the farmers thought it unnecessary to provide water. Breeding was generally uncontrolled and the progeny of the most active breeding ram or buck was often the main source of replacement males. The overall offtake rates were 20% for sheep and 24% for goats. Several flocks had no offtake while four (three flocks of goats and one of sheep) reported offtake rates of 65 to 80%.

Excreted/secreted products of developing Taenia saginata metacestodes.

Excretions and secretions (ES) and somatic components of 4, 8, 12 and 16-week-old Taenia saginata metacestodes were biosynthetically radio-isotope labelled by incubating the larvae in the presence of [35S]methionine. Despite their small size, 4-week-old metacestodes produced as much isotope-labelled ES/parasite as older metacestodes, indicating a proportionately greater metabolic activity of the parasite at this age. In situ the 4-week-old metacestodes were surrounded by a marked granulomatous cellular infiltrate which had largely resolved around 8-week-old metacestodes. Examination of the isotope-labelled ES by SDS-PAGE revealed distinct age-specific components from 4- and 12-week-old metacestodes and other ES components which were produced by all the ages of metacestodes examined. In comparison the labelled somatic components were conserved. Antigenic characterization of the ES by immunoprecipitation against a panel of clinically defined bovine sera combined with SDS-PAGE analysis, identified some highly immunogenic parasite products and others which did not elicit an antibody response demonstrable by immunoprecipitation. These components are of interest in relation to the host/parasite relationship, to the construction of diagnostic assays for the detection of T. saginata cysticercosis, and to the immunity that cattle develop against this parasite.

Enhancement of visual perception under conditions of short-term exposure to sensory isolation: a comparison of procedures for altering vigilance.

An experiment was conducted to determine the pre- and posttest performance of subjects on a signal-detection task for the following three experimental conditions: sensory isolation, sensory alertness, and sensory relaxation. All subjects were assessed on 36 pretest and 36 posttest trials. Each block of 36 trials consisted of 12 "strong signals," 12 "weak signals," and 12 "no signals." Exposure durations for each experimental condition lasted for one hour. Analyses showed significant improvements in hits from the pretest trials to the posttest trials on the "strong" and "weak signals" for the sensory isolation condition. Moreover, on the posttest "weak signal" trials, subjects in the sensory isolation condition scored a significantly greater number of hits than did those in the sensory alertness or sensory relaxation conditions. It was concluded that sensory isolation produces perceptual enhancement, as measured by a signal-detection task.

Productivity of sheep and goats under three management systems at Bamenda, Cameroon.

The productivity of sheep and goats was examined under three management systems. A regime by which each animal received five doses of fenbendazole in a year gave similar results in terms of survival and liveweight gain to monthly dosing. Sheep kept by traditional methods without anthelmintic treatment survived and grew less well than goats. In contrast goats grew better and produced more young under traditional management although they were in general lighter than sheep.

Serum antibody levels to Taenia saginata in cattle grazed on Scottish pastures.

The serum antibody levels to Taenia saginata of three groups of cattle were assessed by an enzyme-linked immunosorbent assay (ELISA). The first group of cattle were from four farms which had a confirmed T saginata cysticercosis outbreak, all of which had cattle classed as infected by ELISA. The second group were from four farms where sewage sludge had been applied to pasture subsequently grazed by the cattle. One of these farms had cattle classed as infected by ELISA. The control cattle, which were all classed as uninfected by ELISA, came from five farms whose pasture had not been treated with sewage sludge. In a wider survey, involving sera from 47 additional farms, the majority could not be distinguished from the control farms in the earlier survey. However, samples from three of the farms had a similar number of positives to two of the known infected farms in the initial survey. Since the ELISA assay may indicate infected herds, farms such as these warrant further investigation.

Variations in Echinococcus granulosus of bovine origin identified by enzyme electrophoresis.

Hydatid cysts of bovine, equine, porcine, ovine, caprine and human origin and also from gerbils used to passage cysts of human origin were obtained from various geographical locations. Extracts from these cysts were compared for the electrophoretic forms of glucose phosphate isomerase. Equine and porcine cyst extracts had identical zymogram patterns. These differed markedly from the zymogram patterns of cysts of ovine, caprine and human origin which appeared identical to the ovine strain. In contrast both types of zymogram patterns were found in extracts from cysts obtained from cattle. This variation seemed to be associated with both geographical location and the fertility of the cysts.

Attempted infection of calves with Taenia crocutae cysticerci and their subsequent serological response.

The susceptibility of naive cattle to infection with cysticerci of Taenia crocutae was tested using three six- to nine-month-old Ayrshire bull calves, previously unexposed to infection with taeniid eggs. One calf was given 10,000 T crocutae eggs orally, another 5000 hatched unactivated oncospheres orally and the third 5000 hatched and activated oncospheres by intravenous injection. None of the calves contained viable cysticerci at post mortem examination 15 to 17 weeks later. All three calves contained small numbers of lesions in the liver and lesions were also present in the lungs of the calf which received oncospheres intravenously. All the calves developed an antibody response which was most pronounced in the calf given hatched unactivated oncospheres orally.